Well Apple does provide the drivers needed to get Vista up and running, and I've not heard of any issues with Macs in particular running Vista. In fact, they reportedly run Vista better than most PCs. The real issue is lack of drivers for peripherals like printers, scanners, and so on. And... since it is much more of a resource hog than Windows XP is, you will likely see a performance hit on anything you run, especially games.

Any reason why you HAVE to use the Windows version of Office? There is a Mac version, though there are some differences in features available between the two.